How to Troubleshoot the Transmission in Vehicles

by Contributing Writer; Updated June 12, 2017

The transmission in your Vehicles uses special fluid that helps lubricate the transmission gears. Vehicles use a planetary gear system and need sufficient lubrication to prevent the gears from seizing or grinding on each other. Once the gears become damaged, you will likely need major transmission service by a qualified, professional, transmission specialist. Before you have any work done on your Vehicles transmission, however, you need to troubleshoot the problem.

Under The Hood:

 How to Troubleshoot the Transmission in a Chevy Truck

Start your Chevy's engine and let the engine warm up. When the needle on the temperature gauge is at or near the middle of the gauge, the engine will be sufficiently warm.

Open the truck's hood and pull the looped handle out of the transmission filler neck in the back of the engine bay. This will the transmission dipstick.

Wipe the oil off the end of the dip stick and put the transmission oil dipstick all the way back into the filler neck.

Pull the dipstick back out of the filler neck and check the end of the dipstick. The oil on the end of the dipstick should be between the upper and lower marks on the end of the dipstick. If your Chevy is an automatic, the transmission fluid should be red in color. If it is a manual transmission, the oil should be a dark, deep brown color. If the oil level is not between the upper and lower marks on the end of the dipstick, you'll need to pour more transmission fluid into the filler neck until you reach the proper oil level.

Check for transmission or gear slipping. If your transmission slips out of gear while driving, it is most likely the clutch or the torque converter (depending on whether you drive a standard or automatic) on your Chevy truck.

Items you will need

  • Shop rag

 How to Troubleshoot the Transmission in a 1995 Chevy

Check the spot area where you park your Chevy overnight. If there is a spot of red fluid, then you have a transmission leak. A leak of transmission fluid can lead to a broken transmission.

Take your Chevy out for a drive to heat up the transmission. Park the vehicle and let it remain running. Pop up the hood and find the transmission dipstick. It will be located on the side of the engine near the rear firewall.

Pull the dipstick out and clean it off with the old rag. Put the dipstick back in and take it back out right away. Examine the level of the transmission fluid. If the transmission fluid is low then add fluid. Low fluid is a major cause of transmission failure.

Make sure that the fluid is clean. If the fluid is dirty and smells burnt, then it needs to be changed.

Turn off your Chevy and let it cool down for a couple of hours.

Shimmy yourself under your Chevy and find the transmission. The transmission is connected right behind the engine. Use the light to find any leaks, broken wires or parts that have come loose.

Items you will need

  • Car keys

  • Old rag

  • Light

 How to Troubleshoot a Transmission in a 2001 Chevy Blazer

Check for leaks by crawling underneath the truck and inspecting the transmission. The location of the leak is important, so wipe off any leaking fluid and wait for the leak to return. Fluid can leak from the front and drip down or back due to the forces of driving. If the leak is coming from the crease around the transmission's pan, then the pan gasket could be at fault. If the leak is coming from the front of the unit where it meets the engine, the main front seal is damaged.

Check the condition of the fluid from the dipstick, located behind the engine oil filler neck at the rear of the motor. The fluid should be a red color and translucent. Brown or black oil is a clear indicator of internal transmission damage. It should have a sweet smell, not a burnt smoky odor. The oil is key to cooling the unit; if this fluid is burned up and dark, then the heat will not dissipate and internal parts such as the torque converter can become damaged quite easily.

Check the level of fluid on the dipstick while the truck is running. Crank the truck up and leave it in park while pulling the dipstick and inspecting where the fluid mark is on the tip of the stick. Low level from leaks can cause the transmission to shift sluggishly, or not at all, as the fluid in the pressurized channels within the transmission lowers beyond functionality. Top the fluid off by pouring it into the dipstick pipe with a funnel, and drive the truck for several miles. If the fluid leaks back out, and there is no leaking, then the torque converter or internal damage can be "eating" the fluid or burning it up quickly. In this case, the transmission can actually become a hazard to the rest of the truck and should be inspected by a shop immediately.

Check trouble codes from the computer by linking a scanning tool to the terminal underneath the driver's kick panel. Most auto parts stores will check these codes for free, and a code may have appeared that will give an indication of the issue.

Check the electrical connections to the upper electric vacuum switches on the 4L60E transmission by following their wires and checking to ensure the wire plugs are seated. This newer transmission uses sensor input from the engine to shift gears, unlike the 700R4 before it. Without these sensors in place and functional, the transmission will have trouble shifting.

Items you will need

  • Lint free cloth

  • Dextron 3 transmission fluid